Iodine is a trace mineral that doesn’t get much attention during pregnancy, but is vital for the development of thyroid hormones for both you and your baby.
Read on to learn more about this nutrient, why you need it, how to get it, and what happens if you get too much.
The Importance of Iodine During Pregnancy
Iodine plays a major role in the body, especially during pregnancy!
The main role that iodine plays is to help produce thyroid hormones, and the amount that is absorbed depends on how much is consumed.
It is a mineral that must be consumed through food, supplements, and cannot be made by the body.
To maintain normal thyroid levels during pregnancy, your thyroid works extra hard and produces 50% more hormones than when you are not pregnant.
Your developing baby and placenta use some of these hormones, and needs are increased partially because your baby’s developing thyroid needs a continuous supply of iodine to continue to grow normally (Source: Journal of Thyroid Research).
During breastfeeding, the only source of iodine in your baby’s diet is via breastmilk, which is why, in some countries, needs are increased during pregnancy and breastfeeding.
Iodine Dosage When Pregnant: How Much Should I Be Getting?
Suggested iodine dosages vary from country to country.
Recommended daily allowances have been adjusted in some countries to help prevent deficiency, as needs can increase during pregnancy.
Those at the highest risk for iodine deficiency include pregnant and lactating women and their young infants.
In the United States, iodine is added to salt to help prevent iodine deficiency. The recommendations for pregnant and lactating women range from 220-290mg, respectively (Source: NIH).
However, in the UK, the daily recommendation is 150 micrograms, with no increase during pregnancy (Source: Cambridge). Supplementation is not common in the UK.
The UNICEF/WHO/ICCIDD recommends a daily intake for women during pregnancy of 250 micrograms per day, and 150 micrograms per day for all other adults (Source: British Journal of Nutrition).
The European Food Safety Authority recommends 200 micrograms per day throughout pregnancy.
If you’re not sure how much you should be taking for your individual circumstances, then ask your health professional during your next check-up.
Iodine Deficiency During Pregnancy and Birth Defects
Iodine deficiency can lead to problems for you and your baby, including hypothyroidism, premature birth, stillbirth, and miscarriage (Source: Journal of Thyroid Research).
Research shows that maternal iodine deficiency can also lead to birth defects including mental deficiency and delay, and general cretinism or learning difficulties.
Worldwide, iodine deficiency is the leading preventable cause of mental retardation (Source: JCEM).
In an interesting study done on Chinese children, it was discovered that the IQ of children living in areas where iodine deficiency was virtually nonexistent was over 12 points higher than children living in iodine-deficient areas! (Source: Hindawi).
Another small study found a greater prevalence of ADHD in children born in areas of mild to moderate iodine deficiency compared to those born in areas with no iodine deficiency. (Hindawi)
In summary, iodine deficiency during pregnancy can only lead to poor outcomes for you and your baby. Therefore, adequate iodine intake is crucial.
Luckily, there are plenty of foods that are rich in iodine that you can consume safely throughout your pregnancy – and we’ve included a comprehensive list below.
Should I Take an Iodine Supplement When Pregnant?
Iodine supplementation during pregnancy is common in some countries, even when risk for deficiency is low.
Most women will get moderate amounts of iodine from their daily diet, and government systems are aiding in this goal. The list of foods (above) should help you incorporate more into your diet.
Some countries have iodized tap water (as a form of purification), which would help to increase consumption (Source: IGN)
Water from certain aquifers has higher iodine content. Iodized salt is an easy way to get iodine too, unless you have to limit your salt intake.
Prenatal vitamins also contain iodine, but the amount varies widely between brands and sources.
Sea kelp compared to potassium iodide provides different amounts, and because supplements are not regulated by the FDA, it’s difficult to choose one brand or type over the other (Source: JTR).
It would be best to discuss iodine supplementation with your medical professional to see if it is something that you need, or if you can get it through your diet.
Since everyone is different, a urine test and thyroid testing could be done to determine existing iodine levels before adding a supplement during your particular pregnancy.
Limited research shows that supplementation could lead to abnormal thyroid hormone levels, and could increase risk for hypothyroidism after pregnancy (Source: American Journal of Epidemiology).
That being said, the benefits far outweigh the risks when considering if you should take an iodine supplement.
Is Excess Iodine Dangerous During Pregnancy?
The Tolerable Upper Limit (UL) for iodine ranges from the WHO’s recommendation of 500 micrograms to 1100 micrograms from the IOM.
Research shows that moderate consumption of iodine can lead to increased fetal iodine levels, which may actually help to increase cognition (source: Journal of Thyroid Research)
There is, however, an interesting secondary effect that can occur after excessive iodine consumption, called the Wolff-Chaikoff effect. This is when the thyroid stops producing thyroid hormones as a response to high levels of iodine.
The pregnant mother’s thyroid is able to adjust, but the growing baby’s thyroid cannot adjust its regulation until 36 weeks into pregnancy.
This means that excessive iodine consumption could potentially lead to fetal hypothyroidism (known as an ‘underactive thyroid’).
That being said, excess iodine usually leaves the body when you pee, so the risk for toxicity or excessive intake is usually quite low (Source: JTR).
Iodine deficiency during pregnancy can also lead to thyroid disease for your baby, so it’s important to consume a diet rich in iodine, and use daily prenatal vitamins to help ensure that you are meeting your daily needs.
Not getting enough iodine is far more common than getting too much, though if you think you might be consuming excessive iodine, talk to your healthcare provider.
Can Too Much Iodine Cause Miscarriage?
There is truth behind the phrase “too much of a good thing”.
That being said, there is NO proof or direct correlation between iodine supplementation and miscarriage.
The risk for miscarriage is also not directly related to iodine deficiency.
The relationship between iodine deficiency and pregnancy loss was researched via the LIFE study, involving over 500 women throughout their pregnancies.
Iodine levels were monitored and it was found that in almost 60% of the participants, being deficient in iodine wasn’t reflected in the prevalence of miscarriage (Source: Nutrients Journal).
Hopefully, this can help to reassure you that iodine deficiency does not directly mean an increased risk for miscarriage, and no research suggests that too much iodine can lead to miscarriage.
13 Iodine-Rich Foods for Pregnancy
Getting enough iodine doesn’t have to be difficult!
To help you reach optimum levels during pregnancy, here are some foods that are both rich in iodine and easily incorporated into your pregnancy diet:
Iodine Content: 10 grams dried nori = 232 micrograms (Source: NIH)
Seaweed is one of the richest sources of iodine that we can consume.
During pregnancy, it’s important to choose seaweed from trusted sources; if seaweed comes from contaminated water, it could increase the risk of foodborne illness.
A great way to incorporate seaweed into your diet is by eating vegetable sushi rolls! The rice, fresh vegetables, and seaweed are all nutritious, delicious, and safe to consume during pregnancy.
2. Whole Wheat Bread
Iodine Content: 1 slice = 198 micrograms (Source: NIH).
Iodine amounts in bread vary from brand to brand, but fortification has become common practice in most established companies.
A slice or two of toast with butter and jam/jelly in the morning or a grilled cheese sandwich in the afternoon are a couple of easy ways to get your daily iodine allowance, along with fiber and other nutrients.
If you follow a gluten-free diet because of Celiac disease, this is one that you’d have to avoid.
3. Cod Fish
Iodine Content: 3 ounces cod = 158 micrograms (Source: NIH).
Cod is one of the most mild-tasting fish types on the market, and is safe to eat during pregnancy if it’s fully cooked (for more on cod during pregnancy, including other considerations like mercury, check out our article here).
Cod can be prepared in a variety of ways, including baked, fried, or grilled. Its mild flavor is suitable for pregnancy, when stronger flavors or smells might cause nausea.
Try a lemony baked cod over quinoa or brown rice for a delicious, filling dinner that can help to provide a majority of the iodine that you need in a day!
You could also try flaked cod in fish tacos for a lighter alternative to ground beef.
4. Greek Yogurt
Iodine Content: 1 cup = 116 micrograms (Source: NIH).
Not only is dairy a great source of iodine, it’s also high in protein, calcium, and potassium, making it a nutritional powerhouse during (and after) pregnancy.
Greek Yogurt is double-strained, meaning that it is thicker than traditional yogurt; more of the liquid has been removed.
Another thick yogurt is Skyr, an Icelandic form of strained yogurt. Greek Yogurt with berries and granola is a filling, nutritious, and easy breakfast that you can eat during pregnancy.
You could also make a smoothie with fruit and yogurt if you prefer to drink, rather than eat, in the morning.
We have a dedicated guide to the best yogurt brands for pregnancy, too!
5. Cooked Oysters
Iodine Content: 3 ounces = 93 micrograms (Source: NIH).
Oysters might be something that you either crave or can’t stand during pregnancy!
The texture might be off-putting to some, but others might find that they very much like the soft, chewy texture.
Consuming undercooked shellfish during pregnancy is not recommended, as the risk for foodborne illness is high.
Rather, steamed, grilled, roasted, baked, or stewed oysters are all wonderful alternatives.
Oyster stew and oyster dressing are two traditional oyster dishes. Oysters could also be steamed with mussels and served with pasta for a filling, iodine-rich meal.
Oysters are something that need to be prepared properly to be safe during pregnancy, so you might want to read our guide on oyster safety for pregnant women.
Iodine Content: 1 cup = 85 micrograms (NIH).
If the texture of yogurt is not for you, drinking a few glasses of milk could help to meet your daily iodine needs during pregnancy.
It’s one of the best pregnancy drink choices besides water, too.
Milk could be added to cereal, mixed into a smoothie, or even consumed warm; consider steeping some decaffeinated tea in warm milk for a relaxing alternative to a traditional latte.
If you are lactose intolerant, consider lactose-free milk, which would still contain iodine.
7. Iodized Salt
Iodine Content: ¼ teaspoon = 76 micrograms (NIH).
Since 1924, manufacturers in the USA have been adding iodine to salt to help reduce the development of goiters, which are a direct result of iodine deficiency (Source: Harvard).
Salt that has been iodized will say so on the label. In other countries, it’s rarer to find iodized salt, but check the ingredients.
However, it’s important to know that salt contributes to high blood pressure, fluid retention, kidney disease, and overall exacerbation of cardiovascular disease.
If you do need to limit salt intake, there are plenty of other foods on this list that you can consume to help meet your daily iodine needs.
8. Enriched Pasta (Cooked in Iodized Salted Water)
Iodine Content: 1 cup cooked = 36 micrograms (Source: NIH).
Most pastas are enriched with nutrients, including iodine, and cooking pasta in iodized salted water helps to increase iodine intake.
9. Cooked Egg
Iodine Content: 1 large egg = 26 micrograms (Source: NIH).
Not only do eggs provide iodine, but they are also one of the best sources of protein available.
During pregnancy, eating eggs can surely help to meet your needs and keep you feeling fuller, longer. Scrambled eggs with whole-wheat toast can be a fantastic, easy breakfast that is ready in minutes and is easy to digest, which may be beneficial during periods of nausea or morning sickness.
Eggs can also be eaten hard-boiled, in a quiche, or poached. Eggs should always be fully cooked -including the yolk, unless you live in the UK and eat Lion Mark eggs. You can read all about safe egg cookery during pregnancy here.
10. Chocolate Ice Cream
Iodine Content: ½ cup = 21 micrograms (Source: NIH).
If eating chocolate ice cream during pregnancy is a way to get your daily iodine requirements, then count us in!
Chocolate ice cream is great in moderation, and can be made into a milkshake if you’d like; consider adding a few tablespoons of peanut butter or a banana to your milkshake to give it another layer of flavor!
If you have to avoid excess sugar because of gestational diabetes, consider a lower sugar chocolate ice cream; it can still provide iodine without spiking your blood sugar.
11. Beef Liver
Iodine Content: 3 ounces = 14 micrograms (Source: NIH).
There is a concern for Vitamin A toxicity with excessive liver consumption, but a few servings here and there will likely not cause any harmful side effects. You can read about Vitamin A during pregnancy here.
Beef liver is also a great way to help meet your iodine needs, along with a healthy dose of protein.
Liver can be eating with gravy, creamed potatoes, or onions – just make sure it’s cooked all the way through before tucking in.
12. Cheddar Cheese
Iodine Content: 1 ounce = 14 micrograms (Source: NIH).
Cheddar cheese does not provide as much iodine as some of the other foods, but it’s a great snack that is also a good protein source.
It’s wonderful with fresh fruit and bread for a snack, or melted into eggs for a protein-packed breakfast.
Aged cheddar may be better for someone with lactose intolerance, so try a small bit and work up from there.
You can read our full guide to cheddar cheese during pregnancy here.
13. Cooked Shrimp (Prawns)
Iodine Content: 3 ounces = 13 micrograms (Source: NIH)
Shrimp provides a significant amount of protein along with a moderate amount of iodine to help meet your daily needs.
Most shrimp are safe, and low in mercury, but you should check where they’re from, too – we have a pregnancy shrimp safety guide here.
You could try eating shrimp with cocktail sauce (especially if you are craving spice), sauteed with pasta for a delicious, restaurant-quality meal at home, or in a coconut-based curry for a hearty, filling meal.
In conclusion, iodine deficiency is the leading risk for congenital delay and mental retardation in children, and can lead to hypothyroidism (an underactive thyroid) for you and your baby.
It’s crucial to consume adequate iodine throughout your pregnancy, and the list of foods above should help you get enough in your diet.
The risk for iodine toxicity is low, and the benefits of iodine far outweigh the risks of consuming too much iodine.
Luckily, eating a wide variety of iodine-rich foods can help you meet these daily needs. If a supplement is needed, check with your medical professional to confirm that the one you are using is only made of the highest quality products, too.
This article has been reviewed and approved for publication in line with our editorial policy.